1. Field of the Invention
The present invention relates to a high-temperature motor pump and a method of operation thereof, and more particularly to a high-temperature motor pump for pumping a high temperature liquid for use in a boiler system or a nuclear power plant.
2. Description of the Related Art
Conventionally, in order to pump a high temperature liquid, there has been used a motor pump in which a pump and a motor for driving the pump are connected by a common rotatable shaft. In such a conventional high-temperature motor pump, a usual contact-type bearing cannot be used for supporting the rotatable shaft since the bearing is not provided with proper lubrication due to the raised temperature of the bearing portion. In one trial to solve the above lubrication problem, non-contact type magnetic bearings are provided at both ends of the rotatable shaft, and a coolant is supplied into a gap of the bearing portion as needed.
However, in the above conventional high-temperature motor pump, since the space required for the magnetic bearing mechanism is large, the size of the entire motor pump and a space for installation thereof as well as production costs are increased. Particularly, because of a long passage for the coolant, the cost for circulating the coolant in the passage also becomes high.